Chemical Vapour Deposition (CVD) of wear resistant coatings on cemented carbide cutting tools has been in industrial practice for many years. Coatings such as TiCN and Al2O3 have shown to improve the wear resistance on cutting inserts in cutting of many different materials. A combination on an inner layer of TiCN and an outer layer of α-Al2O3 can be found on many commercial cutting inserts aimed for turning of for example steel.
It is an object of the invention to provide an alumina coated cutting tool insert with improved performance in cutting operations. It is a further object of the invention to provide a coated cutting tool with improved wear resistance, for example a higher resistance to crater wear and an enhanced resistance to flank wear of the cutting edge. Another object of the invention is to provide a cutting tool with high performance in turning of steel, such as alloyed steels, carbon steels and tough hardened steels.